| Cover Cover | Oct. 15, 2020 |
| Cover [Abstract] | |
| Document Type | 8-K |
| Document Period End Date | Oct. 15, 2020 |
| Entity Registrant Name | BP Midstream Partners LP |
| Entity Incorporation, State or Country Code | DE |
| Entity File Number | 001-38260 |
| Entity Tax Identification Number | 82-1646447 |
| Entity Address, Address Line One | 501 Westlake Park Boulevard |
| Entity Address, City or Town | Houston |
| Entity Address, State or Province | TX |
| Entity Address, Postal Zip Code | 77079 |
| City Area Code | 281 |
| Local Phone Number | 366-2000 |
| Written Communications | false |
| Soliciting Material | false |
| Pre-commencement Tender Offer | false |
| Pre-commencement Issuer Tender Offer | false |
| Title of 12(b) Security | Common Units, Representing Limited Partner Interests |
| Trading Symbol | BPMP |
| Security Exchange Name | NYSE |
| Entity Emerging Growth Company | false |
| Amendment Flag | false |
| Entity Central Index Key | 0001708301 |
